Process of preparing highly-oxidized manganese compounds



J. C. ADELL. PROCESS OF PREPARING HIGHLYVOXIDIZED MANGANESE COMPOUNDS.

APPLICATION FILED AUG. 20. l9l7.

Patented Oct. 14, 1919.

Jar 527. 271" JAMES C. ADELL, 0F CLEVELAND, OHIO.

PROCESS OF PREPARING HIGHLY-OXIDIZED MANGANESECOMPOUNDS.

Specification of Letters Patent.

PatentedOct. 1d, 1919.

Application filed August 20, i917. Serial at. 187,044.

To all whom it may concern:

Be it known that I, JAMES C. ADELL, a

citizen of the United States, residing at Cleveland, in the county of Guyahoga and State of Ohio, have invented a certain new and useful Improvement in Processes of Preparing Highly-Oxidized Manganese Compounds, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings.

-This invention relates to a method of oxidizing manganese compounds, as for example, in making alkali permanganates from commercial oxids of manganese, or for making pure manganese d1ox1d from 'lmpure manganese oxids. The invention further relates to a method of recoverin manganese compounds in a pure and pre erably highly oxygenated condition from impure ores containing the same and especially from hematite ores which are frequently contaminated with phosphorus, sulfur and silicon.

The invention also provides a method for purifying ironores from phosphorus and sulfur. This process has been devised primarily for the treatment of certain large deposits of ore in the Duluth-Superior vdistricts whose composition is approximately:

Fie O 55% MnO 401% Silicon, phosphorus and sulfur 5%- Owing to the phosphorus, this ore is now practically valuless since neither the iron nor the manganese can be secured by any practicable known "method without such contamination as to render it uselessindustrially; and even if the phosphorus were not present, an ore containing the indicated amount of manganese is worth only two or three dollars a ton more than one which is free from manganese; while pure pyrolusite under present market conditions is worth ap proximately one thousand dollars per ton and has never brought less than two hundred to three hundred dollars. The invention is not, however, restricted to this ore or to this product. v I

The objects of my invention are the provision of a feasible industrial process for re-- covering manganese 1n a commercial scale from an impure ore such as above indicated alt-hou h not restricted to this particular ore; t e provision of a recovery process tially whereby such manganese is recovered in a highly oxygenated condition such as a di- "oxid or permanganate; the provision of a process whereby sulfur, phosphorus and other objectionable elements are' entirely removed; the provision of a new, improved, cheap, and' expeditious process whereby alkall permanganates can be produced directly from pyrolusite or even from other manganese oxids, whether pure or impure; the provision of a process which when applied to impure hematite ores will yield the hematite in pure condition; the provision of a new and improved method of securing pure manganese dioxid from alkali permanganates; while other objects and advantages will appear as the description proceeds.

In the drawings accompanying and forming a part of this application I have illustrated in a very diagrammatic and somewhat conventional manner the various steps of my improved process. In these drawings Figure 1 represents the dry portion of the process, and Fig. 2 represents the wet portion of the same, it being understood that each is read from left to right in the usual manner. According to my improved process I first crush the raw ore to a reasonable degree of fineness, preferably between sixty and one.

reagent, but excessive silica should be avoided.

i I next mix the crushed ore with substanan equal weight of alkali hydrate. This may consist either of potash or soda or a mixture of the two. In cases where the manganese content is subsequently to be re- .moved and sold separately I prefer to employ'a mixture of approximately potassium hydroxid one part and sodium hydroxid nineteen arts in order to facilitate the subsequent usion. In. case the permanganate product is desired one-of the pure-alkalls,

generally the potash, is preferably used.

Sodium or potassium carbonate can be employed-with results wholly as satlsfactory, although with no particular gain in cheapness since waterfree carbonate costs approximately as much as the hydroxid when the comparative amounts of alkali present are considered; These ingredients are thoroughly mixed together in any suitable or convenient manner as by .a rotary concrete mixer shown at A in Fig. 1 and transferred to a suitable container as indicated conventionally at B. I have shown these containers as consisting of open iron pots capable of holding a few hundred pounds of charge, although in large scale operations I anticipate the possibility of employing a continuous process such as an elongated inclined trough or rotary kiln. When the pot has become charged it is transferred as shown 'at C to the position shown at D in the top of a furnace E- of any suitable construction whereby the pot and contents can be heatedto a temperature of six hundred to eight hundred degrees centigrade whereupon the alkali combines with the manganese present to form otassium permanganate, this operation belng carried out in contact with the air so as to effect the necessary oxidation. I have shown a blowing tube F projecting into the heated pot and receiving from a blower G a current of air which has previously been heated by passing through the coil H in the furnace stack. After a short time, generally only a few minutes although the time depends upon the amount of the charge and the thoroughness of the blowing, the resulting mass will be found to possess a bright blue color streaked with the brown hematite which has not been permanently altered (although I apprehend that itmay have performed an important catalytic function in the reaction).

As soon as the reaction is largelycomplete', the pot is removed as shown at I to make room for a succeedin pot, and is transferred to the position J, w ere steam from a tube K is blown therein. This steam has the effect of completing the oxidation to the rmanganate condition, of any manganate eft unchanged by the air, and my experience is that melts subjected to this steam treatment sufl'er less loss by decomposition and reversion in subsequent manipulationsthan those not treated in this manner. However, I do not assert that this steam treatment is im-' perative, and I am not repared to offer any explanation of its mo e of operation, but merely state'the-result of my observation, that such a treatment is beneficial but not essential, when certain products such as pure permanganates are desired. The contents of v the pot are molten at the time the steam is blown therein, and after the conclusion of the steam treatment the pot isleft to cool partially and its contents to harden as indicated at L.

As soon as the pot and its contents have cooled below the boiling temperature of water the mass is lixiviated with hot water. This can be rformed in the same vessel if particular] in case the pot be only filled wit the solidified mixture;

' with the alkalis.

' ther fact that the solidified mixture adheres rather closely to the pot, I preferably immerse the whole receptacle in a tank M of hot water as shown at N, the bottom of the tank being preferably provided with a grating O and with a draw-01f ho per P closed by suitable Valves Q whereby t be precipitated ferric sesquioxid can be drawn off into a car R. The .mass in the pot being of a porous nature and the perman'ganates being highly soluble, the receptacle can soon be removed in inverted condition as shown at S and returned for a succeeding use. 7

The slud e' from the bottom of the tank M ordinari y consists of almost pure ferric sesquioxid in a compact granular form, not gelatinous or adherent. It is free "from sulfur and phosphorus and largely from silicon, all of which form soluble compounds If the ore should contain cobalt, nickel, titanium, or the like, these oxids will remain with the iron. Also in case any of the manganese oxid in the original melt were oxidized by the air only to manganate, this manganate ,would be broken up by the steam into permanganate, alkali hydroxid, and manganesedioxid, the last named then remaining with the iron.

The liquid in the tank consistsof a concentrated solution of alkali permanganate together with excessof alkali and the sulfur, phosphorus, and silicon salts of that alkali, and, if any'aluminul'n were present in the ore, the aluminate of that alkali. Ordinarily the percentage of these impurities is very small and, it .is possible to evaporate the solution and crystallize the permanganate in pure form-directly. Owing to the fact that the present market price of potassium permanganate-is approximately eight mode of effecting this oxidation, it being necessary merely to add a quantity of oxid of iron as a catalyzer and blow air through the mixture, whereupon prompt and'com plete oxidation takes place, practically all instead of only two thirds thereof as heretofore. I None of the iron ap ars in the resultant solution; even a $111 ocyanid test gives negative results. Furthermore any oxid of manganese will operate equally as well as the dioxid, the earbonate of the alkali will enter the reaction equally as well the manganese coming out as permanganate with the addition of a quantity of manganese oxid, the impurities can be oxidized to a condition 'where they will unite with the alkali to form a soluble salt. Iron ores purified by my process should have a peculiar value for electric furnace smeltlng.

In case the supply of permanganate produced by my process should exceed the market demand, my process also provides a mode of reducing it to manganese dioxid of a peculiarly pure and active grade. The concentrated solution is withdrawn through a pipe T to an electrolytic apparatus U where it is electrolyzed in a rapid and preferably continuous manner, which breaks up the permanganate into the alkali hydroxid and manganese dioxid. The former remains in solution and passes off through the pipe V to the evaporating pan W where it is evaporated to dryness ready for a subsequent cycle of operations. The manganese dioxid is precipitated in the electrolysis apparatus in the form of a black sludge or mud which is drawn off from time to time through the pipe X. I prefer the congether so as to secure a low internal resistance and a high current density. I carry the electrolysis only to the point necessary to dissociate the permanganate which, owing to the normal instability of the solution, is easily and rapidly efiected.

It is well known that. dilute permanganate solutions will be decomposed with considerable rapidity when left in contact with the air, and insoluble, complex oxids of manganese being precipitated. However, by employing hot concentrated alkaline solu-' tions I experience little or no loss from this reaction. Also by employing a high current density in the electrolysis together with a, high over voltage, I precipitate the manganese in the form of the dioxid. I have used with good results and prefer to employ a current. of approximately 5 amperes per square decimeter at a potential of 3 to 10 volts, although I do not restrict myself to this and have not yet ascertained the operative limits of potential and current.

The sulfur, phosphorus and silicon originally present in the ore become dissolved in the alkali solution, and if dissociated by the electrolysis, recomb ne and pass away with the recovered caustic, leaving the manganese and iron in a pure state. For this and other reasons I find a slight but continuous shrinkage of the caustic, amounting under ordinary conditions to approximately ten per cent. for each cycle. In case the alkali carbonates are employed at first instead of the alkali hydroxids, the effect of the electrolysis is still to recover the alkali as caustic. In fact a mixture of caustic and carbonate can be employed with perfectly satisfactory results. v

In casemetallic manganese is eventually desired, as for steel making, it is perfectly feasible to operate the electrolytic cell at a lower potential so as to produce a lower oxid of manganese, althou h I can find no advantage in such a modification compara ble with the increased time required.

In fact if the manganese output is desired solely for reduction purposes and not as dioxid or permanganate, -I recommend the omission of the steam injection, since the presence of alkali manganate in solution serves only to effect the deposition of lower oxids of manganese, which are even easier to reduce than the dioxid. In this particular case the steam treatment is a detriment as causing some manganese loss in the lixiviating tank.

It will be obvious, that my process can be started at any point or stopped at any point, that great varieties of apparatus may be employed and that my invention is limited only by the terms of the annexed claims and the prior state of the art.

- Having thus described my invention, what I claim is 1. In the process of making alkali permanganates the step which consists in heating an oxid of manganese together with an alkali hydroxid or carbonate in air to low redness in contact with iron oxid.

2. The process of separating manganese oxids from hematite, which contains the steps of heating the powdered ore in contact with alkali hydroxi-d or carbonate to fusing temperature andstirring air into the mixture. 3. The process of converting alkali manganates into permanganates Which consists in stirring air into the fused mixture in the presence of iron oxid.

4. The process of preparing alkali permanganates from manganitic hematite ore which contains the steps of fusing the powdered ore with alkali carbonate or hydroxid, blowing air into the fused mixture, cooling, and lixiviating with water.

5. In the process of making alkali permanganates the steps which consist in fusing an oxid of manganese together with an alkali hydroxid or carbonate in contact with iron oxid and afterward blowing ganates which consists in fusing an oxid of manganese together with an alkali hydroxid or carbonate in contact with iron oxid, introducing air and steam into the fused mixture, cooling, and lixiviating with water.

7. The process of separating the mixed oxids of iron and manganese which consists in fusing the mixture with an alkali hydroxid or carbonate, s'tirring air into the fused mixture, cooling, lixiviating the resultsignature.

JAMES C. ADELL. 

